How is my refund calculated? When can I expect to receive my refund?To request a refund for overpayment, follow these steps. Complete the Overpayment Refund Request Form. Clearly state the decision regarding the refund. This brief but important letter notifies a customer that he or she has overpaid you. It can serve as a very good customer relations letter. In this article, we'll show you how to write a refund request letter template that not only grabs attention but also persuades companies to act in your favor. This form must be filled out completely and legibly, or the refund request will be denied. Over Payment Refund Letter To Customers Template.